D-15 Axles to Drum: studs or bolts

On my D-15 the axles are secured to the drum with six studs (3/8 I think), a coarse thread going into the drum and a fine thread for a nut on the outer. But one is missing and a couple are different lengths. Thinking of just replacing with six bolts. Seems simpler. Why use the studs? Would Grade 8 be a good idea? Want strength because this is where the power transfers to the wheels...but have heard Grade 8 may be brittle? Ideas from the experienced?? Thanks.

Studs are used and course thread is used on the "stationary" thread. By that I mean the stud is threaded into the hub and the studs are not ment to be removed during normal serviceing of the truck Course thread is stronger on a streight pull, fine thread takes more torque on a rotateing nut. Each thread is being used for its streith and not its weakness. repeated threading and un threading of bolts can wear the threads in the hub. Studs are not hard to come by, just go back with them. I use a light thread-locker to make sure the course end stays in the hub on next dis-assembly. I don't use red locktite, as you may need to change a broken or damaged stud at some point.
Double nuts can be used on the fine thread end, to install the stud in the hub if you dont have the proper stud setter.

There are floating axles out there that use bolts instead of studs.
However, I agree with CB again, use studs.
As I get older, I like stock more and more. Unless your studs show signs of wear I say leave them .
I think the stud situation is funny.
If you go to my full service parts store in Dinuba and ask for a stud the countermen will point to each other and laugh.
In the 30 plus years I've been going there they've never carried studs despite having the largest selection of metric and grade 8 fasteners around.
If you go into a Home Depot or Lowe's they carry a huge selection of cotter pins, studs, washers, bolts, etc. Some of it is stainless.
However, you'll pay about 5 times for the same bolt or washer at those stores than you will at my parts store.
Online, the world is your oyster.

Most if not all that use bolts are modern, where the expected life span is measured in years and not decades. Things have got cheaper, not better.
will bolts work? sure, is it worth the trouble of finding studs? thats a call you'll have to make.

Thanks Cornbinder and Smog Guy, just the kind of input I was looking for. Will go with the studs. Knew there must be an engineering reason behind the use of the studs...